Gases from a melting reduction plant or a coal/melt-down gasifier contain large quantities of ultrafine dust particles, i.e. dust particles having a size of approximately 1 micron, which can only be separated with very considerable difficulty in a wet washer using suitable washer types, such as annular clearance washers and accompanied by very high pressure losses or gas velocities, because they almost have the properties of a gas.
If use is not made of an added wetting agent for environmental protection reasons and due to the large quantities required, it is scarcely possible to obtain dust content values below 5 mg/m.sup.3 , (wherein m.sup.3 is norm cubic meter or one cubic meter at 0.degree. C. and 1.01325 bar; or 3.times.10.sup.-7 pounds per cubic foot), even with high energy costs.
As the gas from the aforementioned plants is an export gas with a relatively high calorific value, which can be advantageously utilized in a gas combustion turbine with very high efficiency of approximately 46% for current generation purposes, the just content following washing should be below 5 mg/m.sup.3.